Bobbin rotation restraining means for sewing machines



June A,5, 1951 2,555,658

' H. RITTER BOBBIN ROTATION RESTRAINING MEANS FOR SEWING MACHINES Filed Jan. 29, 1949 30a I Y Herman z'i'fltleI/I Patented June 5, 1951 BOBBIN ROTATIN RESTRAINING MEANS FOR SEWING MACHINES Herman Ritter, Cranford, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey fApplication January 29, 1949, Serial No. '73,638

' 5 Claims. 1 This invention relates to horizontal axis rotary hook stitch-forming mechanisms for sewing machines of the lock stitch type and it has `as its primary object to provide an improved and simplied means to apply to the bobbin of lower thread suicient restraint to prevent overrunning of the bobbin and spilling of thread therefrom.

Another object of the invention is to provide, in a device of this nature, readily adjustable means for varying the rotation restraining force applied to the bobbin.

As used herein, the term "bobbin is intended to mean any Wound mass of thread, as used in lock stitch sewing machines, whether or not the thread is wound upon a spool having a central hub and side flanges as shown in the drawings. In other words, the invention is equally adaptable to stitch forming mechanisms which use a socalled "cop of thread, the wound cop being the equivalent of the wound bobbin shown in the drawings.

Drawings depicting a preferred form of the invention are annexed as a part of this disclosure and in such drawings Fig. 1 is a vertical sectional view showing certain stitch forming elements of a lock stitch sewing machine embodying the present invention.

Fig. 2 is an outer fac-e view of a thread-case comprising one of the elements of the stitch forming mechanism.

Fig. 3 is an inner face view of the thread-case showing my improved bobbin rotation restraining device therein.

Fig. 4 is an enlarged :horizontal section taken on the lines 4 4 of Figs. 1 and 3.

Fig. 5 is an enlarged vertical section `taken substantially on the line 5--5 of Fig. 3, together with a portion of the thread-case carrier.

Fig. 6 is a detail perspective view of the improved bobbin rotation restraining element.

Referring more specifically to the drawings, the invention is disclosed as embodied in a sewing machine stitch forming mechanism of the lock stitch type, comprising a rotary hook I secured upon a horizontal drive shaft 2 and formed with an inner annular raceway 3 adapted to receive the peripheral flange 4 of a thread-case carrier 5. This carrier has a cavity 6, a back wall in the form of a conventional diameter bar l and a central thread-case supporting stud 8 carried by the diameter bar. Secured to and cooperating with the carrier 5, to house a bobbin B, is a cuplike thread-case 9 having a front wall I0, a central sleeve II adapted to t upon the stud 8, and

a skirt-portion I2 fitted within the cavity 6 in the thread-case carrier. Conventional latch. means, designated generally as L, is carried by the thread-case and engages the outer end portion of the pin 8 to releasably lock the thread-case 9 to its carrier 5. The bobbin may comprise 'a central hub I3 (journaled upon the sleeve II) upon which the thread T is wound, and side flanges I4. The rotary hook I takes loops of needle thread t from a reciprocating eye-pointed needle n and passes those loops about the bobbin B, thereby forming conventional lock stitches as is Well understood.

The improved bobbin rotation restraining device preferably comprises a thin spring steel member S of substantially J-shape, having a shank portion I5, and a curved foot portion IS. The shank portion is secured flatwise upon the inner face of the front wall Ill of the threadcase 9 by a screw I1 passing through an aperture I8 in the upper end of the shank and threaded into a tapped hole I9 in the wall IIJ. As shown most clearly in Figs. 1 and 4, the foot portion I5 of the member S is bent laterally out of the plane of the shank portion I 5 and bears against the adjacent side flange III of the bobbin B, thereby forcing the rear flange of the bobbin against the back wall of the thread-case carrier. Pressure of the foot portion I6 against the bobbin flange creates friction which retards rotation of the bobbin, thus preventing overrunning of the bobbin and the consequent spilling of thread.

The amount of friction applied to the bobbin may be regulated by means of an adjusting screw 2li threaded in a tapped hole 2| in the front wall I@ of the thread-case 9. As shown most clearly in Figs. 3 and 5, the inner end of the screw 20 bears upon the outer face of the shank kportion I5 of the rotation restraining device S adjacent its lower end.

Referring to Fig. 5 it will be seen that inward adjustment of the screw 20 causes an increase in the pressure applied to the bobbin by the foot portion of the spring member S and thereby further restricts rotation of the bobbin. Outward adjustment of the screw has the opposite effect.

' To prevent accidental shifting of the screw 20,

be of considerable length, giving maximum flexibility; that it may be'secured in a conventional thread-case Without taking up any substantial amount of room; and that it applies the restraining force to the outer marginal portion of the bobbin ange Where it is most effective.

Having thus set forth the nature of the invention, what I claim herein is:

1. A stitch forming mechanism -for a sewingV machine including a hook member rotatable on a horizontal axis, a thread-case carrier journaled in said hook member, a cup-shaped thread-case in said thread-case carrier and having a front wall and a cylindrical'skirt portion forming 'a bobbin-receiving cavity in which a bobbin is rotatably mounted; and a bobbin rotation restraining device mounted in said thread-case and comprising a fiat spring member'having a shank portionlsecured iiatwise to the inner face of said front wall and an oiset foot portion located out of the plane of said shank portion and arrangedk to press against the bobbin in said cavity.

2. A stitch forming mechanism for a sewing machine including a rotatable hook member, a thread-case carrier journaled in said hook member, a cup-shaped thread-case in said threadcase carrier and having a vertical front Wall and a skirt portion forming a bobbin-receiving cavity in which a bobbin is rotatably mounted; va bobbin rotation restraining device mounted in .said thread-case and comprising a spring metal member having a shank portion secured natwise to the inner face of said front wall and an oiiset foot portion located inwardly of the plane of said shank portion and arranged to press against a bobbinin said cavity; and manually adjustable means carried by the front wall of said threadcase to vary the location of said foot portion relative to said front wall to vary the amount of pressure applied by said foot portion to said bobbin.

3. A stitch forming mechanism for a Sewing machine including a rotatable hook member, a thread-case carrier, a cup-shaped thread-case in said thread-case carrier and having a front wall and a skirt portion'iorming a bobbin-receiving cavity in which a bobbin is rotatably mounted; a

.bobbin rotation restraining device mounted in said thread-case and comprising a spring metal member having a shank portion secured fiatwise to the inner face of said front wall and an offset foot vportion located inwardly of the plane of said shank portion and arranged to press against 4 a bobbin in said cavity; and an adjusting screw threaded through said front Wall and bearing against said bobbin rotation restraining device to vary the offset position of said foot portion and thereby vary the amount of pressure applied Y by said foot portion to said bobbin.

4. A stitch forming mechanism for a sewing machine including a rotary hook, a thread-case carrier journaled in said hook and having an.

open-face cavity and a rear wall; a cup-shaped bobbin-holding thread-case fitted within said cavity and having a front wall; and a bobbin rotation vrestraining device located within said thread-case and comprising a substantially J- shaped spring metal member having a shank portion fixedly secured to the inner face of the front wallrof said thread-case and a foot portion deflected inwardly out of the plane of said shank portion and adapted to bear upon a bobbin in said thread-case and `to force the bobbin into frictional contact with the rear wall of said thread-case carrier.

5. A stitch forming mechanism for a sewing machine including a rotary hook, a 'thread-case carrier journaled in said hook and having an open-face cavity and a rear wall; a cup-shaped bobbin-holding thread-case fitted within said cavity and having a front Wall and a skirt portion affording a bobbin-receiving cavity in which a bobbin is rotatably mounted; a bobbin rotation restraining device located within said threadcase and comprising a substantially J-shaped spring metal member having a shank portion scvcured flatwise to the inner face of the front Wall of said thread-case and' an offset foot portion located inwardly of the plane of said shank portion l and arranged to press against -a bobbin in said bobbin-receiving cavity Vto force the bobbin into irictional contact with said rear Wall of the thread-case carrier; and an adjustingy screw threaded through the front wall of said threadcase and bearing against said bobbin rotation restraining device to vary the amount of pressure applied by said foot portion to said bobbin.

HERMAN RITTER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Great Britain Dec. 8, 1927 

